EAGER: Optical Coherence Elastography (OCE): A novel tool for rapid, nondestructive, spatially resolved quantification of mesoscale biofilm mechanical properties

[01:105]细菌群落附着在表面形成生物膜，这在工程生物反应器和自然环境中都很重要。尽管生物膜结构作为生物膜生长和活性的重要介质，但人们对生物膜结构与控制生物膜中生物量保留的力学特性之间的关系知之甚少。为了解决这一知识差距，pi建议开发一种称为光学相干弹性成像的新方法，用于快速定量3D绘制生物膜的机械特性。项目团队将开发光学相干弹性成像方法，并使用它来分析混合培养生物膜的特性和动态，这些生物膜代表了用于生物脱氮的生物膜。将围绕两个具体目标开展工作：1)开发一种动态光学相干弹性成像方法，用于环境生物膜中弹性模量的中尺度无损测绘；2)利用光学相干弹性成像技术量化混合培养氮循环生物膜中尺度生物膜力学性能、形态和性能之间的关系。光学相干弹性成像的初步应用将把杨氏模量和剪切模量的中尺度梯度与生物膜粗糙度、内部孔隙度和厚度的变化联系起来。在这些重要的环境生物膜的发展过程中，无损弹性成像将使中尺度结构和机械特征的时间序列测量成为可能。因此，该项目促进了对环境生物膜中物理结构和机械特性之间的关键但鲜为人知的相互关系的理解。生物膜的宏观特征，如生物量积累和化学转化速率，已知与中尺度生物膜结构和力学性能有关，但绝大多数关于生物膜结构的工作都集中在微观尺度上。光学相干弹性成像将首次实现在中尺度上对生物膜形态和机械特性进行同步定位、实时、无创、原位测绘。提出的光学相干弹性成像方法采用剪切波换能器在生物膜中传播局部变形。然后通过相敏光学相干层析成像对变形进行连续成像。通过将变形的传播速度与局部密度和弹性或粘弹性特性联系起来，获得了空间分辨的中尺度生物膜力学性能分布。光学相干弹性成像最近被应用于生物医学研究，但它是一种全新的生物膜表征方法。本文的研究结果将为阐明中尺度生物膜特性、微尺度生物膜组成和环境生物膜中紧急系统功能之间的相互作用提供新的可能性。本项目将资助一名博士生和一名本科生。项目实验系统将用于为西北大学的核心实验课程设计实验，并为K-12学生和社区团体提供示范。

1701105Wells, George F.Bacterial communities attached to surfaces form biofilms which are important in both engineered bioreactors and natural environments. Despite the importance of biofilm structure as an essential mediator of biofilm growth and activity, little is known about the relationship between biofilm structure and mechanical properties that control retention of biomass in biofilms. To address this knowledge gap, the PIs propose to develop a novel methodology, termed Optical Coherence Elastography, for rapid quantitative 3D mapping of mechanical properties in biofilms.The project team will develop the Optical Coherence Elastography method and use it to assay properties and dynamics of mixed-culture biofilms representative of those employed for biological nitrogen (N) removal. Efforts will be organized around two specific objectives: 1) Develop a dynamic Optical Coherence Elastography method for mesoscale nondestructive mapping of elastic moduli in environmental biofilms; and, 2) Employ Optical Coherence Elastography to quantify the relationship between mesoscale biofilm mechanical properties, morphology, and performance in mixed culture N-cycling biofilms. Initial applications of Optical Coherence Elastography will relate mesoscale gradients in Young's and Shear moduli to variation in biofilm roughness, internal porosity and thickness. Nondestructive elastography will enable time-series measurement of mesoscale structural and mechanical features during development of these essential environmental biofilms. Thus, this project advances understanding of critical yet poorly understood interrelationships between physical structure and mechanical properties in environmental biofilms. Macroscale biofilm characteristics such as biomass accumulation and chemical transformation rates are known to be linked to mesoscale biofilm structure and mechanical properties, yet the vast majority of work on biofilm structure has focused on the microscale. Optical Coherence Elastography will enable, for the first time, co-located, real-time, non-invasive, in situ mapping of biofilm morphology and mechanical properties at the mesoscale. The proposed Optical Coherence Elastography methodology employs a shear wave transducer to propagate localized deformations in biofilms. Deformations are then continuously imaged via phase sensitive optical coherence tomography. The spatially resolved mesoscale biofilm mechanical property distribution is obtained by relating the speed of propagation of deformations to local density and elastic or viscoelastic properties. Optical Coherence Elastography has recently been applied for biomedical research, but is an entirely new approach to biofilm characterization. Results of the proposed work will open new possibilities to elucidate the interplay between mesoscale biofilm properties, microscale biofilm composition, and emergent system function in environmental biofilms. This project will support one Ph.D. student and as undergraduate student. Project experimental systems will be used to design experiments for a core laboratory course at Northwestern and demonstrations for outreach to K-12 students and community groups.